Details

Autor(en) / Beteiligte

• Damude, Howard G
• Zhang, Hongxiang
• Farrall, Leonard
• Ripp, Kevin G
• Tomb, Jean-Francois
• Hollerbach, Dieter
• Yadav, Narendra S

Titel

Identification of bifunctional Delta 12/ omega 3 fatty acid desaturases for improving the ratio of omega 3 to omega 6 fatty acids in microbes and plants

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2006-06, Vol.103 (25), p.9446-9451

Erscheinungsjahr

2006

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• We report the identification of bifunctional Delta 12/ omega 3 desaturases from Fusarium moniliforme, Fusarium graminearum, and Magnaporthe grisea. The bifunctional activity of these desaturases distinguishes them from all known Delta 12 or omega 3 fatty acid desaturases. The omega 3 desaturase activity of these enzymes also shows a broad omega 6 fatty acid substrate specificity by their ability to convert linoleic acid (LA), gamma -linolenic acid, di-homo- gamma -linolenic acid, and arachidonic acid to the omega 3 fatty acids, alpha -linolenic acid (ALA), stearidonic acid, eicosatetraenoic acid, and eicosapentaenoic acid (EPA), respectively. Phylogenetic analysis suggests that omega 3 desaturases arose by independent gene duplication events from a Delta 12 desaturase ancestor. Expression of F. moniliforme Delta 12/ omega 3 desaturase resulted in high ALA content in both Yarrowia lipolytica, an oleaginous yeast naturally deficient in omega 3 desaturation, and soybean. In soybean, seed-specific expression resulted in 70.9 weight percent of total fatty acid (%TFA) ALA in a transformed seed compared with 10.9%TFA in a null segregant seed and 53.2%TFA in the current best source of ALA, linseed oil. The ALA/LA ratio in transformed seed was 22.3, a 110- and 7-fold improvement over the null segregant seed and linseed oil, respectively. Thus, these desaturases have potential for producing nutritionally desirable omega 3 long-chain polyunsaturated fatty acids, such as EPA, with a significantly improved ratio of omega 3/ omega 6 long-chain polyunsaturated fatty acids in both oilseeds and oleaginous microbes.